Polymer film comprising a copolyamide of a diamine, a dimer acid and a lactam

ABSTRACT

The present invention relates to a polymer film (P), comprising at least one copolyamide, wherein the copolyamide has been prepared by polymerizing at least one lactam (A) and a monomer mixture (M). The present invention further relates to a process for producing the polymer film (P) and to the use of the polymer film (P) as packaging film.

The present invention relates to a polymer film (P), comprising at leastone copolyamide, wherein the copolyamide has been prepared bypolymerizing at least one lactam (A) and a monomer mixture (M). Thepresent invention further relates to a process for producing the polymerfilm (P) and to the use of the polymer film (P) as packaging film.

Polyamides are of particular industrial significance, since they featurevery good mechanical properties; more particularly, they have highstrength and toughness, good chemical stability and high abrasionresistance. They are used, for example, for production of fishing lines,climbing ropes and carpet backings. In addition, polyamides are employedfor production of packaging films and packaging sleeves.

An overview of the use as packaging films and packaging sleeves and onthe production thereof is described, for example, in Encyclopedia ofPolymer Science and Engineering 2nd ed., vol. 7, pp. 73-127, Vol. 10,pp. 684-695 (John Wiley & Sons, Inc., 1987). However, the polyamidefilms described therein are very stiff, and have low tear propagationresistance and high density.

For packaging films and packaging sleeves, therefore, copolyamides whichcombine positive properties of different polyamides are often used. Theprior art discloses various copolyamides.

EP 0 352 562 describes films composed of copolyamides, wherein thecopolyamides have been prepared from ε-caprolactam and preferably 1 to10 parts by weight of a dimer acid and a diamine. The copolyamides canthen be used for production of flat or blown films. They are likewisesuitable for production of composite films.

A disadvantage of the films of copolyamide described in EP 0 352 562 isthat they have a relatively low tear propagation resistance, a highmodulus of elasticity and a low puncture energy.

DE 28 46 596 describes shaped bodies made from a copolyamide formed fromcaprolactam, fatty acid dimers and hexamethylenediamine. However, thethermoplastics described cannot be extruded to a film.

It was an object of the present invention to provide a polymer film thatcomprises a polyamide and has the disadvantages of the polymer filmsdescribed in the prior art only to a reduced degree, if at all. Thepolymer film should additionally be producible in a very simple andinexpensive manner.

This object is achieved by a polymer film (P) comprising at least onecopolyamide prepared by polymerizing the following components:

-   (A) 15% to 84% by weight of at least one lactam,-   (B) 16% to 85% by weight of a monomer mixture (M) comprising the    following components:    -   (B1) at least one C₃₂-C₄₀ dimer acid and    -   (B2) at least one C₄-C₁₂ diamine,        where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B).

It has been found that, surprisingly, the polymer film (P) of theinvention has high tear propagation resistance both in extrusiondirection and at right angles thereto. This is particularly advantageouswhen the polymer film (P) of the invention is used as packaging film.

Furthermore, the polymer film (P) of the invention has hightransparency, and high low-temperature toughness. It is additionallyadvantageous that the polymer film (P) of the invention is less stiffthan the polymer films (P) described in the prior art that comprise apolyimide or a copolyamide. The polymer film (P) of the invention alsohas a low modulus of elasticity and a high puncture resistance in thedry state. The high puncture resistance is likewise of particularsignificance when the polymer film (P) is used as packaging film.

The invention is elucidated in detail hereinafter.

Polymer Film (P)

According to the invention, the polymer film (P) comprises at least onecopolyamide.

In the context of the present invention, “at least one copolyamide” isunderstood to mean either exactly one copolyamide or a mixture of two ormore copolyamides.

The polymer film (P) has a thickness, for example, in the range from 0.1μm to 1 mm, preferably a thickness in the range from 5 to 500 μm andespecially preferably in the range from 20 to 100 μm.

The present invention therefore also provides a polymer film (P) inwhich the polymer film (P) has a thickness in the range from 0.1 μm to 1mm.

The polymer film (P) may, in addition to the at least one copolyamide,comprise at least one further polymer (FP).

In the context of the present invention, “at least one further polymer(FP)” means either exactly one further polymer (FP) or a mixture of twoor more further polymers (FP).

Polymers suitable as the at least one further polymer (FP) are allpolymers known to those skilled in the art. It will be apparent that theat least one further polymer (FP) is different than the at least onecopolyamide.

Preferably, the at least one further polymer (FP) is selected from thegroup consisting of polyolefins, poly(ethyl-vinyl alcohols),poly(ethyl-vinyl acetates), polyethylene terephthalates, polyvinylidenechlorides, maleic anhydride-grafted polyolefins, polyesters andionomers. More preferably, the at least one further polymer (FP) isselected from the group consisting of polyolefins, polyethyl-vinylalcohols), poly(ethyl-vinyl acetates), polyethylene terephthalates,polyvinylidene chlorides and maleic anhydride-grafted polyolefins. Mostpreferably, the at least one further polymer (FP) is selected from thegroup consisting of polyolefins, maleic anhydride-grafted polyolefinsand ethyl-vinyl alcohols.

If the at least one further polymer (FP) is selected from the groupconsisting of polyolefins, it is preferable that, in addition, maleicanhydride-grafted polyolefins are used as at least one further polymer(FP). It is possible here that the at least one further polymer (FP)used is a mixture of polyolefins and maleic anhydride-graftedpolyolefins. It is likewise possible that, when the polymer film (P) isa multilayer film described below, the polymer film (P) comprises atleast one first further layer of at least one further polymer (FP),where the at least one further polymer (FP) of the first further layeris selected from the group consisting of maleic anhydride-graftedpolyolefins and the polymer film (P) comprises at least one secondfurther layer of at least one further polymer (FP), where the at leastone further polymer (FP) of the second further layer is selected fromthe group consisting of polyolefins. The polymer film (P) in that casepreferably comprises the first further layer between the first layercomprising the at least one copolyamide and the second further layer.

Polyolefins as such are known to those skilled in the art. Preferredpolyolefins are polypropylene (PP), low-density polyethylene (LDPE),linear low-density polyethylene (LLDPE) and very low-densitypolyethylene (VLDPE).

Linear low-density polyethylene (LLDPE) is a copolymer of ethylene andat least one C₄-C₈-α-olefin. Linear low-density polyethylene (LLDPE)features long polymer chains with short side chains. The length of theside chains in linear low-density polyethylene (LLDPE) is typicallyshorter than in low-density polyethylene (LDPE) and in medium-densitypolyethylene (MDPE). The melting point of linear low-densitypolyethylene (LLDPE) is preferably in the range from 110 to 130° C.; itsdensity is in the range from 0.91 to 0.93 g/cm³.

Very low-density polyethylenes (VLDPE) are copolymers of ethylene and atleast one C₄-C₈-α-olefin. They typically have a melting point in therange from 110 to 130° C. and a density in the range from 0.86 to <0.91g/cm³. The proportion of C₄-C₈-α-olefins in VLDPE is generally higherthan in LLDPE.

In the contact of the present invention, “C₄-C₈-α-olefin” is understoodto mean linear and branched, preferably linear, alkylenes having 4 to 8carbon atoms that are unsaturated in the α position, i.e. have a C—Cdouble bond in the α position. Examples of these are 1-butene,1-pentene, 1-hexene, 1-heptene and 1-octene. 1-Butene, 1-hexene and1-octene are preferred.

Preferred poly(ethylene-vinyl acetates) are copolymers of ethylene withvinyl acetate. For example, they are prepared using in the range from82% to 99.9% by weight of ethylene and in the range from 0.1% to 18% byweight of vinyl acetate, preferably in the range from 88% to 99.9% byweight of ethylene and in the range from 0.1% to 12% by weight of vinylacetate.

Preferred poly(ethylene-vinyl alcohols) are obtainable by complete orpartial hydrolysis of the above-described poly(ethylene-vinyl acetates).For example, the poly(ethylene-vinyl alcohols) comprise in the rangefrom 50 to 75 mol % of ethylene and in the range from 25 to 50 mol % ofvinyl alcohol, based on the total molar amount of thepoly(ethylene-vinyl alcohols).

The polymer film (P) may comprise the at least one further polymer (FP)as a blend (mixture) with the at least one copolyamide.

Furthermore, it is possible and preferable in accordance with theinvention that the polymer film (P) comprises at least one first layercomprising the at least one copolyamide, and the polymer film (P)comprises at least one further layer comprising the at least one furtherpolymer (FP).

In this embodiment, it is preferable that the at least one first layercomprising the at least one copolyamide does not comprise any furtherpolymer (FP).

In the context of the present invention, “at least one first layer”means either exactly one first layer or two or more first layers.

In the context of the present invention, “at least one further layer”means either exactly one further layer or two or more further layers.Two or more further layers are preferred.

It is thus preferable that the polymer film (P) comprises at least onefirst layer comprising the at least one copolyamide, and the polymerfilm (P) also comprises at least one further layer, where the at leastone further layer comprises at least one further polymer (FP) selectedfrom the group consisting of polyolefins, poly(ethylene-vinyl alcohols),poly(ethylene-vinyl acetates), polyethylene terephthalates,polyvinylidene chlorides and maleic anhydride-grafted polyolefins.

The present invention thus also provides a polymer film (P), in whichthe polymer film (P) comprises at least one first layer comprising theat least one copolyamide, and the polymer film (P) comprises at leastone further layer, where the at least one further layer comprises atleast one further polymer (FP) selected from the group consisting ofpolyolefins, poly(ethylene-vinyl alcohols), polyethylene-vinylacetates), polyethylene terephthalates, polyvinylidene chlorides andmaleic anhydride-grafted polyolefins.

If the polymer film (P), apart from the at least one first layer, doesnot comprise any further layer, the polymer film (P) is also referred toas a monofilm. If the polymer film (P) is a monofilm, it may compriseexactly one first layer and no further layer; it is likewise possiblethat it comprises two or more first layers and no further layer. If thepolymer film (P) comprises two or more first layers and is a monofilm,the two or more first layers all have the same composition.

If the polymer film (P) comprises at least one first layer comprisingthe at least one copolyamide, and at least one further layer comprisingthe at least one further polymer (FP), the polymer film (P) is alsoreferred to as a multilayer film.

For example, the polymer film (P) in that case comprises 1 to 11 firstlayers comprising the at least one copolyamide, and 1 to 13 furtherlayers comprising the at least one further polymer (FP). Preferably, thepolymer film (P) comprises 1 to 5 first layers comprising the at leastone copolyamide, and 1 to 11 further layers comprising the at least onefurther polymer (FP). Especially preferably, the polymer film (P)comprises 1 to 3 first layers comprising the at least one copolyamide,and 1 to 7 further layers comprising the at least one further polymer(FP).

In a preferred embodiment of the present invention, the at least onefirst layer consists of the at least one copolyamide. It is likewisepreferable that the at least one further layer consists of the at leastone further polymer (FP).

In the context of the present invention, the term “polymer film (P)”thus comprises both monofilms and multilayer films.

The present invention therefore also provides a polymer film (P),wherein the polymer film (P) is a monofilm or a multilayer film.

As described above, the polymer film (P) typically has a thickness inthe range from 0.1 μm to 1 mm, preferably in the range from 5 to 500 μmand especially preferably in the range from 10 to 100 μm.

If the polymer film (P) is a monofilm and comprises exactly one firstlayer, the first layer has the same thickness as the polymer film (P),i.e., for example, in the range from 0.1 μm to 1 mm, preferably in therange from 5 to 500 μm and especially preferably in the range from 10 to100 μm. If the polymer film (P) is a monofilm and comprises two or morefirst layers, the thickness of every first layer is typically less thanthe thickness of the polymer film (P). The sum total of the thicknessesof the individual first layers in that case generally corresponds to thethickness of the polymer film (P). For example, the at least one firstlayer comprising the at least one copolyamide in that case has athickness in the range from 0.1 to 100 μm, preferably in the range from0.5 to 50 μm and especially preferably in the range from 0.5 to 15 μm.

If the polymer film (P) is a multilayer film, the thickness of theindividual layers of the polymer film (P), i.e. the thickness of the atleast one first layer comprising the at least one copolyamide, and thethickness of the at least one further layer comprising the at least onefurther polymer (FP), is typically less than the thickness of thepolymer film (P). The sum total of the thicknesses of the individuallayers in that case generally corresponds to the thickness of thepolymer film (P).

For example, the at least one first layer comprising the at least onecopolyamide in that case has a thickness in the range from 0.1 to 100μm, preferably in the range from 0.5 to 50 μm and especially preferablyin the range from 0.5 to 15 μm.

The at least one further layer comprising the at least one furtherpolymer (FP) in that case has a thickness, for example, in the rangefrom 0.1 to 100 μm, preferably in the range from 0.5 to 50 μm andespecially preferably in the range from 0.5 to 15 μm.

The polymer film (P) may comprise at least one adhesion promoter. Thisembodiment is preferred when the polymer film (P) is a multilayer film.

In the context of the present invention, “at least one adhesionpromoter” means either exactly one adhesion promoter or a mixture of twoor more adhesion promoters.

If the polymer film (P) is a multilayer film, the at least one adhesionpromoter may be present together with the at least one copolyamide inthe at least one first layer. It is likewise possible that the at leastone adhesion promoter is present together with the at least one furtherpolymer (FP) in the at least one further layer. Furthermore, it ispossible that the at least one adhesion promoter is present as at leastone additional layer in the polymer film (P). This embodiment ispreferred.

When the at least one adhesion promoter is present as at least oneadditional layer in the polymer film (P), this at least one additionallayer is preferably arranged between the at least one further layercomprising the at least one further polymer (FP), and the at least onefirst layer comprising the at least one copolyamide. The at least onelayer of the adhesion promoter has a thickness, for example, of 0.1 to100 μm, preferably in the range from 0.5 to 50 μm and especiallypreferably in the range from 0.5 to 15 μm.

Suitable adhesion promoters are known as such to the person skilled inthe art. Preferred adhesion promoters are copolymers of ethylene withmaleic anhydride or a copolymer of ethylene with vinyl acetate.Preference is given to a copolymer of linear low-density polyethylene(LLDPE) and maleic anhydride or a copolymer of ethylene and vinylacetate, the copolymer being prepared using >18% by weight of vinylacetate and <82% by weight of ethylene. These copolymers arecommercially available, for example under the Bynel 4105 trade name fromDuPont or Escorene FL00119 from Exxon.

Copolymers of ethylene with maleic anhydride that are used withpreference as adhesion promoters are maleic anhydride-grafted polymersor copolymers of ethylene.

The polymer film (P) may also comprise additives. Additives of this kindare known to those skilled in the art and are selected, for example,from the group consisting of stabilizers, dyes, antistats, tackifiers,anti-blockers, processing auxiliaries, antioxidants, light stabilizers,UV absorbers, lubricants and nucleating aids.

Suitable dyes are organic and inorganic pigments, for example titaniumdioxide provided with a size. Suitable tackifiers are, for example,polyisobutylene (PIB) or ethyl-vinyl acetate (EVA). Suitableantiblocking agents are, for example, silicon dioxide particles orcalcium carbonate particles. Suitable light stabilizers are, forexample, what are called HALS (hindered amine light stabilizers).Processing auxiliaries or lubricants used may, for example, beethylenebisstearamide (EBS) wax. Nucleating aids may, for example, beall kinds of organic or inorganic crystallization nucleators, forexample talc.

The additives may either be present either in the at least one firstlayer or in the at least one further layer. They may be present in justone of these layers; it is likewise possible that they are present ineach of these layers.

Copolyamide

According to the invention, the polymer film (P) comprises at least onecopolyamide prepared by polymerizing the following components:

-   (A) 15% to 84% by weight of at least one lactam,-   (B) 16% to 85% by weight of a monomer mixture (M) comprising the    following components:    -   (B1) at least one C₃₂-C₄₀ dimer acid and    -   (B2) at least one C₄-C₁₂ diamine,        where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B).

The terms “component (A)” and “at least one lactam” are usedsynonymously in the context of the present invention and therefore havethe same meaning.

The same applies to the terms “component (B)” and “a monomer mixture(M)”. These terms are likewise used synonymously in the context of thepresent invention and therefore have the same meaning.

In the context of the present invention, “at least one lactam” meanseither exactly one lactam or a mixture of two or more lactams.Preference is given to exactly one lactam.

According to the invention, the at least one copolyamide has beenprepared by polymerizing 15% to 84% by weight of component (A) and 16%to 85% by weight of component (B); preferably, the copolyamide has beenprepared by polymerizing 40% to 83% by weight of component (A) and from17% to 60% by weight of component (B); especially preferably, the atleast one copolyamide has been prepared by polymerizing from 60% to 80%by weight of component (A) and 20% to 40% by weight of component (B),where the percentages by weight of components (A) and (B) are each basedon the sum total of the percentages by weight of components (A) and (B).

Preferably, the sum total of the percentages by weight of components (A)and (B) adds up to 100% by weight.

It will be apparent that the percentages by weight of components (A) and(B) are based on the percentages by weight of components (A) and (B)prior to polymerization, i.e. when components (A) and (B) have not yetreacted with one another. During the polymerization, the weight ratio ofcomponents (A) and (B) may change.

According to the invention, the copolyamide is prepared by polymerizingcomponents (A) and (B). The polymerization of components (A) and (B) isknown to those skilled in the art. Typically, the polymerization ofcomponents (A) with (B) is a condensation reaction. During thecondensation reaction, component (A) reacts with components (B1) and(B2) present in component (B) and with any component (B3) as describedfurther down that may likewise be present in component (B). This formsamide bonds between the individual components. Typically, component (A)is at least partly in open-chain form during the polymerization, i.e. inthe form of an amino acid.

The polymerization of components (A) and (B) may take place in thepresence of a catalyst.

Suitable catalysts are all catalysts that are known to those skilled inthe art and catalyze the polymerization of components (A) and (B).Catalysts of this kind are known to those skilled in the art. Preferredcatalysts are phosphorus compounds, for example sodium hypophosphite,phosphorous acid, triphenylphosphine or triphenyl phosphite.

The polymerization of components (A) and (B) forms the copolyamide,which therefore receives structural units derived from component (A) andstructural units derived from component (B). Structural units derivedfrom component (B) comprise structural units derived from components(B1) and (B2) and from any component (B3).

The polymerization of components (A) and (B) forms the copolyamide asthe copolymer. The copolymer may be a random copolymer; it is likewisepossible that it is a block copolymer.

In a block copolymer, there is formation of blocks of units derived fromcomponent (B) and of blocks of units derived from component (A). Thesealternate. In the case of a random copolymer, there is alternation ofstructural units derived from component (A) with structural unitsderived from component (B). This alternation is random; for example, twostructural units derived from component (B) may be followed by onestructural unit derived from component (A), which is in turn followed byone structural unit derived from component (B), which is then followedby a structural unit comprising three structural units derived fromcomponent (A).

Preferably, the at least one copolyamide is a random copolymer.

The present invention therefore also provides a polymer film (P) inwhich the at least one copolyamide is a random copolymer.

The preparation of the at least one copolyamide preferably comprises thefollowing steps:

-   a) polymerizing components (A) and (B) to obtain at least one first    copolyamide,-   b) pelletizing the at least one first copolyamide obtained in    step a) to obtain at least one pelletized copolyamide,-   c) extracting the at least one pelletized copolyamide obtained in    step b) with water to obtain at least one extracted copolyamide,-   d) drying the at least one extracted copolyamide obtained in step c)    at a temperature (T_(T)) to obtain the at least one copolyamide.

The present invention therefore also provides a polymer film (P) inwhich the copolyamide is prepared in a process comprising the followingsteps:

-   a) polymerizing components (A) and (B) to obtain at least one first    copolyamide,-   b) pelletizing the at least one first copolyamide obtained in    step a) to obtain at least one pelletized copolyamide,-   c) extracting the at least one pelletized copolyamide obtained in    step b) with water to obtain at least one extracted copolyamide,-   d) drying the at least one extracted copolyamide obtained in step c)    at a temperature (T_(T)) to obtain the at least one copolyamide.

The polymerization in step a) can take place in any reactors known tothose skilled in the art. Preference is given to stirred tank reactors.It is additionally possible to use auxiliaries known to those skilled inthe art to improve the reaction regime, for example defoamers such aspolydimethylsiloxane (PDMS).

In step b), the at least one first copolyamide obtained in step a) canbe pelletized by any methods known to those skilled in the art, forexample by means of strand pelletization or underwater pelletization.

The extraction in step c) can be effected by any methods known to thoseskilled in the art.

During the extraction in step c), by-products that are typically formedduring the polymerization of components (A) and (B) in step a) areextracted from the at least one pelletized copolyamide.

In step d), the at least one extracted copolyamide obtained in step c)is dried. Methods of drying are known to those skilled in the art.According to the invention, the at least one extracted copolyamide isdried at a temperature (T_(T)). The temperature (T_(T)) is preferablyabove the glass transition temperature (T_(G(C))) of the at least onecopolyamide and below the melting temperature (T_(M(C))) of the at leastone copolyamide.

The drying in step d) is typically effected for a period of time in therange from 1 to 100 hours, preferably in the range from 2 to 50 hoursand especially preferably in the range from 3 to 40 hours.

It is envisaged that the drying in step d) will further increase themolecular weight of the at least one copolyamide.

The at least one copolyamide typically has a glass transitiontemperature (T_(G(C))). The glass transition temperature (T_(G(C))) is,for example, in the range from 20 to 50° C., preferably in the rangefrom 23 to 47° C. and especially preferably in the range from 25 to 45°C., determined according to ISO 11357-2: 2014.

The present invention therefore also provides a polymer film (P) inwhich the at least one copolyamide has a glass transition temperature(T_(G(C))), where the glass transition temperature (T_(G(C))) is in therange from 20 to 50° C.

The glass transition temperature (T_(G(C))) of the at least onecopolyamide, in accordance with ISO 11357-2: 2014, in the context of thepresent invention, is based on the glass transition temperature(T_(G(C))) of the dry copolyamide.

In the context of the present invention, “dry” means that the at leastone copolyamide comprises less than 1% by weight, preferably less than0.5% by weight and especially preferably less than 0.1% by weight ofwater, based on the total weight of the at least one copolyamide. Morepreferably, “dry” means that the at least one copolyamide does notcomprise any water and most preferably that the at least one copolyamidedoes not comprise any solvent.

The at least one copolyamide additionally has a melting temperature(T_(M(C))). The melting temperature (T_(M(C))) of the at least onecopolyamide is, for example, in the range from 150 to 210° C.,preferably in the range from 160 to 205° C. and especially preferably inthe range from 160 to 200° C., determined according to ISO 11357-3:2014.

The present invention therefore also provides a polymer film (P) inwhich the at least one copolyamide has a melting temperature (T_(M(C))),where the melting temperature (T_(M(C))) is in the range from 150 to210° C.

The at least one copolyamide generally has a viscosity number (VN_((C)))in the range from 150 to 300 mL/g, determined in a 0.5% by weightsolution of the at least one copolyamide in a mixture ofphenol/o-dichlorobenzene in a weight ratio of 1:1.

Preferably, the viscosity number (VN_((C))) of the at least onecopolyamide is in the range from 160 to 290 mL/g and more preferably inthe range from 170 to 280 mL/g, determined in a 0.5% by weight solutionof the at least one copolyamide in a mixture of phenol/o-dichlorobenzenein a weight ratio of 1:1.

The present invention therefore also provides a polymer film (P) inwhich the at least one copolyamide has a viscosity number (VN_((C))) inthe range from 150 to 300 mL/g, determined in a 0.5% by weight solutionof the at least one copolyamide in a mixture of phenol/o-dichlorobenzenein a weight ratio of 1:1.

Component (A)

Component (A) is at least one lactam.

Lactams are known as such to those skilled in the art. Preference isgiven in accordance with the invention to lactams having 4 to 12 carbonatoms.

In the context of the present invention, lactams are understood to meancyclic amides having, in the ring, preferably 4 to 12 and morepreferably 5 to 8 carbon atoms.

Suitable lactams are selected, for example, from the group consisting of3-aminopropanolactam (propio-3-lactam; β-lactam; β-propiolactam),4-aminobutanolactam (butyro-4-lactam; γ-lactam; γ-butyrolactam),5-aminopentanolactam (2-piperidinone; δ-lactam; δ-valerolactam),6-aminohexanolactam (hexano-6-lactam: ε-lactam; ε-caprolactam),7-aminoheptanolactam (heptano-7-lactam; ζ-lactam; ζ-heptanolactam),8-aminooctanolactam (octano-8-lactam; η-lactam; η-octanolactam),9-aminononanolactam (nonano-9-lactam; θ-lactam; θ-nonanolactam),10-aminodecanolactam (decano-10-lactam; ω-decanolactam),11-aminoundecanolactam (undecano-11-lactam; ω-undecanolactam) and12-aminododecanolactam (dodecano-12-lactam; ω-dodecanolactam).

The present invention therefore also provides a polymer film (P) inwhich component (A) is selected from the group consisting of3-aminopropanolactam, 4-aminobutanolactam, 5-aminopentanolactam,6-aminohexanolactam, 7-aminoheptanolactam, 8-aminooctanolactam,9-aminononanolactam, 10-aminodecanolactam, 11-aminoundecanolactam and12-aminododecanolactam.

The lactams may be unsubstituted or at least monosubstituted. If atleast monosubstituted lactams are used, these may bear, on the nitrogenatom and/or on the carbon atoms of the ring, one, two or moresubstituents independently selected from the group consisting of C₁- toC₁₀-alkyl, C₅- to C₆-cycloalkyl and C₅- to C₁₀-aryl.

Suitable C₁- to C₁₀-alkyl substituents are, for example, methyl, ethyl,propyl, isopropyl, n-butyl, sec-butyl and tert-butyl. An example of asuitable C₅- to C₆-cycloalkyl substituent is cyclohexyl. Preferred C₅-to C₁₀-aryl substituents are phenyl and anthranyl.

Preference is given to using unsubstituted lactams, preference beinggiven to γ-lactam (γ-butyrolactam), δ-lactam (δ-valerolactam) andε-lactam (ε-caprolactam). Particular preference is given to δ-lactam(δ-valerolactam) and ε-lactam (ε-caprolactam), especial preference toε-caprolactam.

Monomer Mixture (M)

According to the invention, component (B) is a monomer mixture (M). Themonomer mixture (M) comprises components (B1), at least one C₃₂-C₄₀dimer acid and (B2) at least one C₄-C₁₂ diamine.

In the context of the present invention, a monomer mixture (M) isunderstood to mean a mixture of two or more monomers, where at leastcomponents (B1) and (B2) are present in the monomer mixture (M).

In the context of the present invention, the terms “component (B1)” and“at least one C₃₂-C₄₀ dimer acid” are used synonymously and thereforehave the same meaning. The same applies to the terms “component (B2)”and “at least one C₄-C₁₂ diamine”. These terms are likewise usedsynonymously in the context of the present invention and therefore havethe same meaning.

The monomer mixture (M) comprises, for example, in the range from 45 to55 mol % of component (B1) and in the range from 45 to 55 mol % ofcomponent (B2), based in each case on the sum total of the molarpercentages of components (B1) and (B2), preferably based on the totalmolar amount of component (B).

Preferably, component (B) comprises in the range from 47 to 53 mol % ofcomponent (B1) and in the range from 47 to 53 mol % of component (B2),based in each case on the sum total of the molar percentages ofcomponents (B1) and (B2), preferably based on the total molar amount ofcomponent (B).

More preferably, component (B) comprises in the range from 49 to 51 mol% of component (B1) and in the range from 49 to 51 mol % of component(B2), based in each case on the sum total of the molar percentages ofcomponents (B1) and (B2), preferably based on the total molar amount ofcomponent (B).

The present invention therefore also provides a polymer film (P) inwhich component (B) comprises in the range from 45 to 55 mol % ofcomponent (B1) and in the range from 45 to 55 mol % of component (B2),based in each case on the total molar amount of component (B).

The sum total of the molar percentages of components (B1) and (B2)present in component (B) typically adds up to 100 mol %.

Component (B) may also additionally comprise a component (B3), at leastone C₄-C₂₀ diacid.

The present invention therefore also provides a polymer film (P) inwhich component (B) additionally comprises a component (B3), at leastone C₄-C₂₀ diacid.

The terms “component (B3)” and “at least one C₄-C₂₀ diacid” are usedsynonymously in the context of the present invention and therefore havethe same meaning.

When component (B) additionally comprises component (B3), it ispreferable that component (B) comprises in the range from 25 to 54.9 mol% of component (B1), in the range from 45 to 55 mol % of component (B2)and in the range from 0.1 to 25 mol % of component (B3), based in eachcase on the total molar amount of component (B).

More preferably, component (B) in that case comprises in the range from13 to 52.9 mol % of component (B1), in the range from 47 to 53 mol % ofcomponent (B2) and in the range from 0.1 to 13 mol % of component (B3),based in each case on the total molar amount of component (B).

Most preferably, component (B) in that case comprises in the range from7 to 50.9 mol % of component (B1), in the range from 49 to 51 mol % ofcomponent (B2) and in the range from 0.1 to 7 mol % of component (B3),based in each case on the total molar amount of component (B).

When component (B) additionally comprises component (B3), the molarpercentages of components (B1), (B2) and (B3) typically add up to 100mole percent.

The monomer mixture (M) may additionally comprise water.

Components (B1) and (B2) and optionally (83) of component (B) may reactwith one another to obtain amides. This reaction is known as such tothose skilled in the art. Therefore, component (B) may comprisecomponents (B1) and (B2) and optionally (B3) in fully reacted form, inpartly reacted form or in unreacted form. Preferably, component (B)comprises components (B1) and (B2) and optionally (B3) in unreactedform.

In the context of the present invention, “in unreacted form” thus meansthat component (B1) is present in the form of the at least one C₃₂-C₄₀dimer acid and component (B2) in the form of the at least one C₄-C₁₂diamine and, if appropriate, component (B3) in the form of the at leastone C₄-C₂₀ diacid.

If components (B1) and (B2) and, if appropriate, (B3) have at leastpartly reacted with one another, components (B1) and (B2) and, ifappropriate, (B3) are at least partly in amide form.

Component (B1)

According to the invention, component (B1) is at least one C₃₂-C₄₀ dimeracid.

In the context of the present invention, “at least one C₃₂-C₄₀ dimeracid” means either exactly one C₃₂-C₄₀ dimer acid or a mixture of two ormore C₃₂-C₄₀ dimer acids.

Dimer acids are also referred to as dimer fatty acids. C₃₂-C₄₀ dimeracids are known as such to those skilled in the art and are typicallyprepared by dimerization of unsaturated fatty acids. This dimerizationcan be catalyzed, for example, by aluminas.

Suitable unsaturated fatty acids for preparation of the at least oneC₃₂-C₄₀ dimer acid are known to those skilled in the art and are, forexample, unsaturated C₁₆ fatty acids, unsaturated C₁₈ fatty acids andunsaturated C₂₀ fatty acids.

Preferably, component (B1) is therefore prepared proceeding fromunsaturated fatty acids selected from the group consisting ofunsaturated C₁₆ fatty acids, unsaturated C₁₈ fatty acids and unsaturatedC₂₀ fatty acids, particular preference being given to the unsaturatedC₁₈ fatty acids.

The present invention therefore also provides a polymer film (P) inwhich component (B1) is prepared proceeding from unsaturated fatty acidsselected from the group consisting of unsaturated C₁₆ fatty acids,unsaturated C₁₈ fatty acids and unsaturated C₂₀ fatty acids.

An example of a suitable unsaturated C₁₆ fatty acid is palmitoleic acid((9Z)-hexadeca-9-enoic acid).

Suitable unsaturated C₁₈ fatty acids are selected, for example, from thegroup consisting of petroselic acid ((6Z)-octadeca-6-enoic acid), oleicacid ((9Z)-octadeca-9-enoic acid), elaidic acid ((9E)-octadeca-9-enoicacid), vaccenic acid ((11E)-octadeca-11-enoic acid), linoleic acid((9Z,12Z)-octadeca-9,12-dienoic acid), alpha-linolenic acid((9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid), gamma-linolenic acid((6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid), calendic acid((8E,10E,12Z)-octadeca-8,10,12-trienoic acid), punicic acid((9Z,11E,13Z)-octadeca-9,11,13-trienoic acid), alpha-eleostearic acid((9Z,11E,13E)-octadeca-9,11,13-trienoic acid) and beta-eleostearic acid((9E,11E,13E)-octadeca-9,11,13-trienoic acid). Particular preference isgiven to unsaturated C₁₈ fatty acids selected from the group consistingof petroselic acid ((6Z)-octadeca-6-enoic acid), oleic acid((9Z)-octadeca-9-enoic acid), elaidic acid ((9E)-octadeca-9-enoic acid),vaccenic acid ((11E)-octadeca-11-enoic acid), linoleic acid((9Z,12Z)-octadeca-9,12-dienoic acid).

Suitable unsaturated C₂₀ fatty acids are selected, for example, from thegroup consisting of gadoleic acid ((9Z)-eicosa-9-enoic acid), eicosenoicacid ((11Z)-eicosa-11-enoic acid), arachidonic acid((5Z,8Z,11Z,14Z)-eicosa-5,8,11,14-tetraenoic acid) and timnodonic acid((5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid).

Component (B1) is especially preferably at least one C₃₆ dimer acid.

The at least one C₃₆ dimer acid is preferably prepared proceeding fromunsaturated C₁₈ fatty acids. More preferably, the C₃₆ dimer acid isprepared proceeding from C₁₃ fatty acids selected from the groupconsisting of petroselic acid ((6Z)-octadeca-6-enoic acid), oleic acid((9Z)-octadeca-9-enoic acid), elaidic acid ((9E)-octadeca-9-enoic acid),vaccenic acid ((11E)-octadeca-11-enoic acid) and linoleic acid((9Z,12Z)-octadeca-9,12-diensäure).

In the preparation of component (B1) from unsaturated fatty acids,trimer acids may additionally form; residues of unreacted unsaturatedfatty acid may also remain.

The formation of trimer acids is known to those skilled in the art.

Preferably in accordance with the invention, component (B1) comprisesnot more than 0.5% by weight of unreacted unsaturated fatty acid and notmore than 0.5% by weight of trimer acid, more preferably not more than0.2% by weight of unreacted unsaturated fatty acid and not more than0.2% by weight of trimer acid, based in each case on the total weight ofcomponent (B1).

Dimer acids (also known as dimerized fatty acids or dimer fatty acids)thus refer generally and especially in the context of the presentinvention to mixtures that are prepared by oligomerization ofunsaturated fatty acids. They are preparable, for example, by catalyticdimerization of unsaturated fatty acids from vegetable sources, in whichcase the starting materials used are especially unsaturated C₁₆ to C₂₀fatty acids. The addition is primarily of the Diels-Alder type, and theresult, according to the number and position of the double bonds in thefatty acids used for preparation of the dimer acids, is mixtures ofprimarily dimeric products having cycloaliphatic, linear aliphatic,branched aliphatic and also C₆-aromatic hydrocarbyl groups between thecarboxyl groups. According to the mechanism and/or any subsequenthydrogenation, the aliphatic radicals may be saturated or unsaturated,and the proportion of aromatic groups may also vary. The radicalsbetween the carboxylic acid groups in that case comprise, for example,32 to 40 carbon atoms. Preference is given to using fatty acids having18 carbon atoms for the preparation, such that the dimeric product thushas 36 carbon atoms. Preferably, the radicals that connect the carboxylgroups of the dimer fatty acids do not have any unsaturated bonds or anyaromatic hydrocarbyl radicals.

In the context of the present invention, C₁₈ fatty acids are thuspreferably used in the preparation. Particular preference is given tousing linolenic acid, linoleic acid and/or oleic acid.

Depending on the reaction regime, the oligomerization described abovegives rise to mixtures comprising mainly dimeric molecules, but alsotrimeric molecules and also monomeric molecules and other by-products.Purification is typically by distillative means. Commercial dimer acidsgenerally comprise at least 80% by weight of dimeric molecules, up to19% by weight of trimeric molecules and not more than 1% by weight ofmonomeric molecules and other by-products.

It is preferable to use dimer acids consisting of dimeric fatty acidmolecules to an extent of at least 90% by weight, preferably to anextent of at least 95% by weight, even more preferably to an extent ofat least 98% by weight.

The proportions of monomeric, dimeric and trimeric molecules and otherby-products in the dimer acids can be determined, for example, by meansof gas chromatography (GC). The dimer acids here, prior to the GCanalysis, are converted to the corresponding methyl esters via the borontrifluoride method (cf. DIN EN ISO 5509) and then analyzed by means ofGC.

A fundamental characteristic of “dimer acids” in the context of thepresent invention is thus that the preparation thereof comprises theoligomerization of unsaturated fatty acids. This oligomerization givesrise primarily to dimeric products, i.e. preferably to an extent of atleast 80% by weight, more preferably to an extent of at least 90% byweight, even more preferably to an extent of at least 95% by weight andespecially to an extent of at least 98% by weight. The fact that theoligomerization thus gives rise predominantly to dimeric productscomprising exactly two fatty acid molecules justifies this name, whichis in common use in any case. An alternative expression for the term“dimer acids” in question is thus “mixture comprising dimerized fattyacids”.

The dimer acids to be used are obtainable as commercial products.Examples of these include Radiacid 0970, Radiacid 0971, Radiacid 0972,Radiacid 0975, Radiacid 0976 and Radiacid 0977 from Oleon, Pripol 1006,Pripol 1009, Pripol 1012, and Pripol 1013 from Croda, Empol 1008, Empol1012, Empol 1061 and Empol 1062 from BASF SE, and Unidyme 10 and UnidymeTI from Arizona Chemical.

Component (B1) has an acid number, for example, in the range from 190 to200 mg KOH/g.

Component (B2)

According to the invention, component (B2) is at least one C₄-C₁₂diamine.

In the context of the present invention, “at least one C₄-C₁₂ diamine”means either exactly one C₄-C₁₂ diamine or a mixture of two or moreC₄-C₁₂ diamines.

In the context of the present compound, “C₄-C₁₂ diamine” is understoodto mean aliphatic and/or aromatic compounds having four to twelve carbonatoms and two amino groups (—NH₂ groups). The aliphatic and/or aromaticcompounds may be unsubstituted or additionally at least monosubstituted.If the aliphatic and/or aromatic compounds are additionally at leastmonosubstituted, they may bear one, two or more substituents that do nottake part in the polymerization of components (A) and (B). Substituentsof this kind are, for example, alkyl or cycloalkyl substituents. Theseare known as such to those skilled in the art. The at least one C₄-C₁₂diamine is preferably unsubstituted.

Suitable components (B2) are selected, for example, from the groupconsisting of 1,4-diaminobutane (butane-1,4-diamine;tetramethylenediamine; putrescine), 1,5-diaminopentane(pentamethylenediamine; pentane-1,5-diamine; cadaverine),1,6-diaminohexane (hexamethylenediamine; hexane-1,6-diamine),1,7-diaminoheptane, 1,8-diaminoctane, 1,9-diaminononane,1,10-diaminodecane (decamethylenediamine), 1,11-diaminoundecane(undecamethylenediamine) and 1,12-diaminododecane(dodecamethylenediamine).

Preferably, component (B2) is selected from the group consisting oftetramethylenediamine, pentamethylenediamine, hexamethylenediamine,decamethylenediamine and dodecamethylenediamine.

The present invention therefore also provides a polymer film (P) inwhich component (B2) is selected from the group consisting oftetramethylenediamine, pentamethylenediamine, hexamethylenediamine,decamethylenediamine and dodecamethylenediamine.

Component (B3)

According to the invention, any component (B3) present in component (B)is at least one C₄-C₂₀ diacid.

In the context of the present invention, “at least one C₄-C₂₀ diacid”means either exactly one C₄-C₂₀ diacid or a mixture of two or moreC₄-C₂₀ diacids.

In the context of the present invention, “C₄-C₂₀ diacid” is understoodto mean aliphatic and/or aromatic compounds having 2 to 18 carbon atomsand two carboxyl groups (—COOH groups). The aliphatic and/or aromaticcompounds may be unsubstituted or additionally at least monosubstituted.If the aliphatic and/or aromatic compounds are additionally at leastmonosubstituted, they may bear one, two or more substituents that do nottake part in the polymerization of components (A) and (B). Substituentsof this kind are, for example, alkyl or cycloalkyl substituents. Theseare known to those skilled in the art. Preferably, the at least oneC₄-C₂₀ diacid is unsubstituted.

Suitable components (B3) are selected, for example, from the groupconsisting of butanedioic acid (succinic acid), pentanedioic acid(glutaric acid), hexanedioic acid (adipic acid), heptanedioic acid(pimelic acid), octanedioic acid (suberic acid), nonanedioic acid(azelaic acid), decanedioic acid (sebacic acid), undecanedioic acid,dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid andhexadecanedioic acid.

Preferably, component (B3) is selected from the group consisting ofpentanedioic acid (glutaric acid), hexanedioic acid (adipic acid),decanedioic acid (sebacic acid) and dodecanedioic acid.

Production of the Polymer Film (P)

The polymer film (P) is preferably produced in a process comprising thefollowing steps:

-   i) providing at least one copolyamide; prepared by polymerization of    the following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        based in each case on the sum total of the percentages by weight        of components (A) and (B), in molten form in a first extruder,-   ii) extruding the at least one copolyamide in molten form provided    in step i) out of the first extruder through a die to obtain a film    of the at least one copolyamide in molten form,-   iii) cooling the film obtained in step ii) of the at least one    copolyamide in molten form, with solidification of the at least one    copolyamide to obtain the polymer film (P).

The present invention therefore also provides a process for producing apolymer film (P) of the invention, comprising the steps of

-   i) providing at least one copolyamide prepared by polymerization of    the following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        based in each case on the sum total of the percentages by weight        of components (A) and (B) in molten form in a first extruder,-   ii) extruding the at least one copolyamide in molten form provided    in step i) out of the first extruder through a die to obtain a film    of the at least one copolyamide in molten form,-   iii) cooling the film of the at least one copolyamide in molten form    obtained in step ii), with solidification of the at least one    copolyamide to obtain the polymer film (P).

In step i), the at least one copolyamide in molten form is provided in afirst extruder.

In the context of the present invention, “a first extruder” means eitherexactly one first extruder or two or more first extruders. Typically, asmany first extruders are used as first layers comprising the at leastone copolyamide are to be present in the polymer film (P).

If the polymer film (P) is to comprise, for example, exactly one firstlayer comprising the at least one copolyamide, exactly one firstextruder is used. If the polymer film (P) is to comprise exactly twofirst layers comprising the at least one copolyamide, exactly two firstextruders are used. If the polymer film (P) is to comprise exactly fivefirst layers comprising the at least one copolyamide, exactly five firstextruders are used.

For example, 1 to 11 first extruders are used, preferably 1 to 5 firstextruders and more preferably 1 to 3 first extruders.

In respect of the at least one copolyamide which is provided in step i),the above-described embodiments and preferences for the at least onecopolyamide present in the polymer film (P) are correspondinglyapplicable.

According to the invention, the at least one copolyamide is provided inmolten form.

In the context of the present invention, “in molten form” means that theat least one copolyamide is provided at a temperature above the meltingtemperature (T_(M(C))) of the at least one copolyamide. “In molten form”thus means that the at least one copolyamide is at a temperature abovethe melting temperature (T_(M(C))) of the at least one copolyamide. Ifthe at least one copolyamide is in molten form, the at least onecopolyamide is free-flowing.

“Free-flowing” means that the at least one copolyamide can be conveyedwithin the first extruder and that the at least one copolyamide can beextruded out of the first extruder.

For example, the at least one copolyamide is provided in step i) at atemperature in the range from 170 to 300° C., preferably in the rangefrom 200 to 290° C. and especially preferably in the range from 230 to280° C., in each case with the proviso that the temperature at which theat least one copolyamide is provided is above the melting temperature(T_(M(C))) of the at least one copolyamide.

The at least one copolyamide can be provided in molten form in the firstextruder by any methods known to those skilled in the art.

For example, the at least one copolyamide can be supplied to the firstextruder in molten form or in solid form. If the at least onecopolyamide is supplied to the first extruder in solid form, it can besupplied to the first extruder, for example, in the form of pelletsand/or in the form of powder. The at least one copolyamide is thenmelted in the first extruder and thus provided in molten form in thefirst extruder. This embodiment is preferred.

In addition, it is possible that components (A) and (B) are polymerizeddirectly in the first extruder and the at least one copolyamide is thusprovided in molten form in the first extruder. Processes for thispurpose are known to those skilled in the art.

In step ii), the at least one copolyamide in molten form is extruded outof the first extruder through a die to obtain a film of the at least onecopolyamide in molten form.

In the context of the present invention, “a die” means either exactlyone die or two or more dies. Preference is given in accordance with theinvention to exactly one die.

Suitable dies are all dies known to those skilled in the art that enableextrusion of a film composed of the at least one copolyamide in moltenform. Examples of dies of this kind are annular dies or slot dies.

Suitable annular dies and slot dies are known as such to those skilledin the art.

If, for example, the step i1) described further down is conducted, it ispreferable that, in step ii), the at least one copolyamide in moltenform from the first extruder is combined with the at least one furtherpolymer (FP) in molten form from the further extruder in the die, forexample in the annular die or in the slot die.

More particularly, in step ii), the at least one copolyamide in moltenform from the first extruder is combined with the at least one furtherpolymer (FP) in molten form from the further extruder in the die in sucha way that the film obtained in step ii) of the at least one copolyamideand the at least one further polymer (FP), each in molten form,comprises at least one first layer comprising the at least onecopolyamide in molten form, and at least one further layer comprisingthe at least one further polymer (FP) in molten form.

For example, the thickness of the film of the at least one copolyamidein molten form is in the range from 0.1 μm to 1 mm, preferably in therange from 5 to 500 μm and especially preferably in the range from 20 to100 μm.

The film of the at least one copolyamide in molten form may, forexample, be a flat film or a tubular film. A tubular film is typicallyobtained when the die used is an annular die; a flat film is obtainedwhen the die used is a slot die.

In step iii), the film obtained in step ii) of the at least onecopolyamide in molten form is cooled down. This results insolidification of the at least one copolyamide to obtain the polymerfilm (P).

Suitable methods of cooling of the film of the at least one copolyamidein molten form are all those known to the person skilled in the art. Forexample, the film of the at least one copolyamide in molten form can becooled by air or water cooling or by contact with a cold surface.

The film of the at least one copolyamide in molten form is cooled downin step iii), for example, to a temperature below the meltingtemperature (T_(M(C))) of the at least one copolyamide to obtain thepolymer film (P). Preferably, the film of the at least one copolyamidein molten form in step iii) is cooled down to a temperature below theglass transition temperature (T_(G(C))) of the at least one copolyamide.

For example, the film of the at least one copolyamide in molten form iscooled down to a temperature in the range from 0 to 100° C., preferablyin the range from 10 to 80° C. and especially preferably in the rangefrom 15 to 50° C., the temperature to which the film of the at least onecopolyamide in molten form is cooled down being below the meltingtemperature (T_(M(C))), preferably below the glass transitiontemperature (T_(G(C))), of the at least one copolyamide.

The present invention therefore also provides a process for producing apolymer film (P) in which, in step iii), the film of the at least onecopolyamide in molten form is cooled down to a temperature below themelting temperature (T_(M(C))) of the at least one copolyamide.

In respect of the polymer film (P) obtained in step iii), theembodiments and preferences described in respect of the polymer film (P)of the invention are correspondingly applicable.

Steps ii) and iii) can be conducted successively or simultaneously.

Preference is given to additionally conducting a step i1) in which atleast one further polymer (FP) in molten form is provided in a furtherextruder.

In that case, the process for producing the polymer film (P) comprisesthe following steps:

-   i) providing at least one copolyamide prepared by polymerizing the    following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B), in molten form in a first extruder,-   i1) providing at least one further polymer (FP) in molten form in a    further extruder,-   ii) extruding the at least one copolyamide in molten form provided    in step i) out of the first extruder through a die and extruding the    at least one further polymer (FP) in molten form provided in step    i1) from the further extruder through the die to obtain a film of    the at least one copolyamide and the at least one further polymer    (FP), each in molten form,-   iii) cooling the film obtained in step ii) of the at least one    copolyamide and the at least one further polymer (FP), each in    molten form, with solidification of the at least one copolyamide    and/or the at least one further polymer (FP) to obtain the polymer    film (P).

In step i1), the at least one further polymer (FP) in molten form isprovided in a further extruder.

In the context of the present invention, “a further extruder” meanseither exactly one further extruder or two or more further extruders.Preference is given to two or more further extruders.

Preference is given to using as many further extruders as further layerscomprising the at least one further polymer (FP) are to be present inthe polymer film (P). For example, 1 to 13 further extruders are used,preferably 1 to 11 further extruders and especially preferably 1 to 7further extruders.

If the polymer film (P), for example, is to comprise exactly one furtherlayer comprising the at least one further polymer (FP), exactly onefurther extruder is used. If the polymer film (P) is to comprise exactlytwo further layers comprising the at least one further polymer (FP),exactly two further extruders are used. If the polymer film (P) is tocomprise exactly five further layers comprising the at least one furtherpolymer (FP), exactly five further extruders are used.

In respect of the further extruder, the embodiments and preferencesdescribed above for the first extruder are correspondingly applicable.

In respect of the at least one further polymer (FP), the embodiments andpreferences described above for the at least one further polymer (FP)that may be present in the polymer film (P) are correspondinglyapplicable.

According to the invention, the at least one further polymer (FP) instep i1) is provided in molten form. “In molten form” means the at leastone further polymer (FP) is provided at a temperature above the meltingtemperature (T_(M(FP)))) of the at least one further polymer (FP). “Inmolten form” thus means that the at least one further polymer (FP) is ata temperature above the melting temperature (T_(M(FP))) of the at leastone further polymer (FP). If the at least one further polymer (FP) is inmolten form, the at least one further polymer (FP) is free-flowing.

“Free-flowing” means that the at least one further polymer (FP) can beconveyed within the further extruder and that the at least one furtherpolymer (FP) can be extruded out of the further extruder.

For example, the at least one further polymer (FP) in step i1) isprovided at a temperature in the range from 120 to 350° C., preferablyin the range from 130 to 300° C. and especially preferably in the rangefrom 140 to 250° C., in each case with the proviso that the temperatureat which the at least one further polymer (FP) is provided is above themelting temperature (T_(M(FP))) of the at least one further polymer(FP).

The at least one further polymer (FP) may be provided in molten form inthe further extruder by any methods known to those skilled in the art.

For example, the at least one further polymer (FP) can be supplied tothe further extruder in molten form or in solid form. If the at leastone further polymer (FP) is supplied to the further extruder in solidform, it can be supplied to the further extruder, for example, in theform of pellets and/or in the form of powder. In that case, the at leastone further polymer (FP) is melted in the further extruder and thusprovided in molten form in the further extruder.

Step i1) is typically conducted simultaneously with step i).

In respect of steps i), ii) and iii) the embodiments and preferencesdescribed above for steps i), ii) and iii) are applicable.

The film obtained in step ii) of the at least one copolyamide and of theat least one further polymer (FP), each in molten form, comprises the atleast one copolyamide in at least one first layer and the at least onefurther polymer (FP) in at least one further layer. Typically, the filmobtained in step ii) has as many first layers comprising the at leastone copolyamide in molten form as first extruders were used in step i)and as many further layers comprising the at least one further polymer(FP) in molten form as further extruders were used in step i1).

It will be apparent that, when step i1) is conducted, the polymer film(P) obtained in step iii) is a multilayer film.

Preferably, the polymer film (P) is stretched. The polymer film (P) canbe stretched after step iii); it is likewise possible to stretch thepolymer film (P) during step iii), i.e. during the cooling of the filmof the at least one copolyamide and optionally of the at least onefurther polymer (FP).

The present invention therefore also provides a process in which thefollowing step is additionally conducted:

-   iv) stretching the polymer film (P) to obtain a stretched polymer    film (SP).

Steps iii) and iv) can be conducted successively or simultaneously.

In the stretching of the polymer film (P), the polymer chains of the atleast one copolyamide become aligned and the crystallinity of the atleast one copolyamide can increase.

It is additionally possible that the polymer chains of any at least onefurther polymer (FP) present in the polymer film (P) are aligned in thecourse of stretching. This can also increase the crystallinity of the atleast one further polymer (FP).

The stretching can be effected by any methods known to those skilled inthe art.

For example, the polymer film (P) can be stretched by guiding it over atleast one roll, preferably a roll system, or by extending it widthwise.If the polymer film (P) is obtained in the form of a tube, it islikewise possible that the polymer film (P) is stretched by blowing airinto the tube of the polymer film (P) and hence stretching the polymerfilm (P). It will be appreciated that combinations of the methods arealso possible.

When the polymer film (P) is guided over at least one roll, preferablythrough a roll system, the polymer film (P) is stretched in extrusiondirection, i.e. lengthwise. If the polymer film (P), by contrast, isextended widthwise, it is stretched at right angles to extrusiondirection.

If the polymer film (P), for stretching, is guided over at least oneroll, preferably through a roll system, the polymer chains of the atleast one copolyamide and of any at least one further polymer (FP) arealigned parallel to the direction in which stretching is effected. Thestretched polymer film (SP) obtained is then uniaxially oriented. Thestretched polymer film obtained (SP) is likewise uniaxially orientedwhen the polymer film (P), for stretching, is extended widthwise. Inthat case too, the polymer chains of the at least one copolyamide and ofany at least one further polymer (FP) are aligned parallel to thedirection in which stretching is effected.

“Uniaxially oriented” means that the polymer chains are alignedessentially in one direction.

If the polymer film (P), for stretching, is guided over a roll systemand additionally extended widthwise, the polymer chains of the at leastone copolyamide and of any at least one further polymer (FP) are alignedparallel to both directions in which stretching is effected. Thestretched polymer film (SP) obtained is then biaxially oriented.

“Biaxially oriented” means that the polymer chains are alignedessentially in two different directions, preferably at right angles toone another.

If the polymer film (P) is obtained in tubular form and the polymer film(P) is stretched by blowing air into the tube of the polymer film (P),the stretched polymer film (SP) obtained is uniaxially oriented.

If the above-described processes for stretching the polymer film (P) arecombined, the polymer film (P) is thus obtained, for example, in tubularform and the polymer film (P) is stretched by blowing air into the tubeof the polymer film (P) and simultaneously guided over rolls andlikewise stretched; thus, the stretched polymer film (SP) obtained isbiaxially oriented.

The polymer film (P) is typically stretched at a temperature above theglass transition temperature (T_(G(C))) of the at least one copolyamideand below the melting temperature (T_(M(C))) of the at least onecopolyamide. It the polymer film (P) is a multilayer film, it is alsopreferable that the polymer film (P) is stretched at a temperature belowthe melting temperature (T_(M(FP))) of the at least one further polymer(FP), especially preferably at a temperature below the meltingtemperature of the at least one further polymer (FP) having the lowestmelting temperature.

The polymer film (P) of the invention can be produced, for example, in acasting process, in a blowing process, in a biaxially oriented polyamidefilm process (BOPA process) or in a multifilm blowing process.

The present invention therefore also provides a polymer film (P) whichis produced in a casting process, in a blowing process, in a biaxiallyoriented polyamide film process or in a multifilm blowing process.

The casting process, the blowing process the biaxially orientedpolyamide film process and the multifilm blowing process are known assuch to those skilled in the art. Typically, the polymer film (P) isstretched in these processes, such that a stretched polymer film (P) isobtained.

A casting process for producing the polymer film (P) preferablycomprises the following steps i-c) to iv-c):

-   i-c) providing at least one copolyamide prepared by polymerizing the    following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B), in molten form in a first extruder,-   ii-c) extruding the at least one copolyamide in molten form provided    in step i-c) out of the first extruder through a die to obtain a    film of the at least one copolyamide in molten form,-   iii-c) cooling the film of the at least one copolyamide in molten    form obtained in step ii-c), with solidification of the at least one    copolyamide to obtain the polymer film (P),-   iv-c) stretching the polymer film (P) obtained in step iii-c) by    guiding the polymer film (P) over at least one roll, preferably over    a roll system, to obtain a stretched polymer film (SP).

In respect of steps i-c) to iii-c) of the casting process, theembodiments and preferences described above for steps i) to iii) of theprocess for producing the polymer film (P) are correspondinglyapplicable.

The die used in the casting process in step ii-c) is typically a slotdie. The film of the at least one copolyamide in molten form obtained instep ii-c) is therefore preferably a flat film, and so the polymer film(P) obtained in step iii-c) and the stretched polymer film (SP) obtainedin step iv-c) are preferably flat films.

In the casting process, steps iii-c) and iv-c) can be conductedsuccessively or simultaneously. Preferably, in the casting process,steps iii-c) and iv-c) are conducted simultaneously; especiallypreferably, steps iii-c) and iv-c) are conducted simultaneously anddirectly after step ii-c).

It is also preferable that, in the casting process, the at least oneroll used in step iv-c), preferably the roll system, is cooled duringstep iv-c).

A blowing process for producing the polymer film (P) preferablycomprises the following steps i-b) to iv-b):

-   i-b) providing at least one copolyamide prepared by polymerizing the    following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B), in molten form in a first extruder,-   ii-b) extruding the at least one copolyamide in molten form provided    in step i-b) out of the first extruder through a die, which is an    annular die, to obtain a tubular film of the at least one    copolyamide in molten form,-   iii-b) cooling the tubular film of the at least one copolyamide in    molten form obtained in step ii-b), with solidification of the at    least one copolyamide to obtain the polymer film (P),-   iv-b) stretching the polymer film (P) obtained in step iii-b) by    blowing air into the tube of the polymer film (P) to obtain a    stretched polymer film (SP).

In respect of steps i-b) to iii-b) of the blowing process, theembodiments and preferences described above for steps i) to iii) of theprocess for producing the polymer film (P) are correspondinglyapplicable.

The die used in step ii-b) of the blowing process is preferably a stackdie, a helical distributor die or a mixed form thereof. These dies areknown to those skilled in the art and are described, for example, in“Blown Film Extrusion” by Kirk Cantor, 2nd Edition, Carl Hanser Verlag,Munich 2011.

Steps iii-b) and iv-b) in the blowing process can be conductedsimultaneously or successively. Preferably, in the blowing process,steps iii-b) and iv-b) are conducted simultaneously.

It will be apparent that, when steps iii-b) and iv-b) in the blowingprocess are conducted simultaneously, the tubular film of the at leastone copolyamide obtained in molten form in step ii-b) is cooled down instep iii-b) and simultaneously stretched by blowing air into the tubularfilm to obtain the stretched polymer film (SP).

A biaxially oriented polyamide film process for producing the polymerfilm (P) preferably comprises the following steps i-o) to iv-o):

-   i-o) providing at least one copolyamide prepared by polymerizing the    following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B), in molten form in a first extruder,-   ii-o) extruding the at least one copolyamide in molten form provided    in step i-o) out of the first extruder through a die to obtain a    film of the at least one copolyamide in molten form,-   iii-o) cooling the film of the at least one copolyamide in molten    form obtained in step ii-o), with solidification of the at least one    copolyamide to obtain the polymer film (P),-   iv-o) stretching the polymer film (P) obtained in step iii-o) by    guiding the polymer film (P) over at least one roll, preferably over    a roll system, and lengthening the width thereof to obtain the    stretched polymer film (SP).

In respect of steps i-o) to iii-o) of the biaxially oriented polyamidefilm process, the embodiments and preferences described above for stepsi) to iii) of the process for producing the polymer film (P) arecorrespondingly applicable.

The die used in the biaxially oriented polyamide film process in stepii-o) is typically a slot die. The film of the at least one copolyamidein molten form obtained in step ii-o) is therefore preferably a flatfilm, and so the polymer film (P) obtained in step iii-o) and thestretched polymer film (SP) obtained in step iv-o) are preferably flatfilms.

In the biaxially oriented polyamide film process, steps iii-o) and iv-o)can be conducted successively or simultaneously; preference is given toconducting steps iii-o) and iv-o) successively. Especially preferably,in the biaxially oriented polyamide film process, steps iii-o) and iv-o)are conducted successively and the polymer film (P) obtained in stepiii-o) is heated prior to step iv-o). It is preferable here that thepolymer film (P) is heated prior to step iv-o) to a temperature abovethe glass transition temperature (T_(G(C))) of the at least onecopolyamide present in the polymer film (P) and below the meltingtemperature (T_(M(C))) of the at least one copolyamide present in thepolymer film (P). The polymer film (P) is then preferably stretched instep iv-o) at the temperature to which it is heated prior to step iv-o).

A multifilm blowing process for producing the polymer film (P)preferably comprises the following steps i-m) to iv-m):

-   i-m) providing at least one copolyamide prepared by polymerizing the    following components:    -   (A) 15% to 84% by weight of at least one lactam,    -   (B) 16% to 85% by weight of a monomer mixture (M) comprising the        following components:        -   (B1) at least one C₃₂-C₄₀ dimer acid and        -   (B2) at least one C₄-C₁₂ diamine,    -   where the percentages by weight of components (A) and (B) are        each based on the sum total of the percentages by weight of        components (A) and (B), in molten form in a first extruder,-   ii-m) extruding the at least one copolyamide in molten form provided    in step i-m) out of the first extruder through a die, which is an    annular die, to obtain a tubular film of the at least one    copolyamide in molten form,-   iii-m) cooling the tubular film of the at least one copolyamide in    molten form obtained in step ii-m), with solidification of the at    least one copolyamide to obtain the polymer film (P),-   iv-m) stretching the polymer film (P) obtained in step iii-m) by    blowing air into the tube of the polymer film (P) and by at the same    time guiding the polymer film (P) over at least one roll, preferably    over a roll system, to obtain a stretched polymer film (SP).

In respect of steps i-m) to iii-m) of the multifilm blowing process, theembodiments and preferences described above for steps i) to iii) of theprocess for producing the polymer film (P) are correspondinglyapplicable.

Preferably, the tubular film of the at least one copolyamide in moltenform is cooled down in a water bath in step iii-m).

In the multifilm blowing process, steps iii-m) and iv-m) can beconducted successively or simultaneously; preference is given toconducting steps iii-m) and iv-m) successively. Especially preferably,steps iii-m) and iv-m) are conducted successively and the polymer film(P) obtained in step iii-m) is heated prior to step iv-m). It ispreferable here that the polymer film (P) is heated prior to step iv-m)to a temperature above the glass transition temperature (T_(G(C))) ofthe at least one copolyamide present in the polymer film (P) and belowthe melting temperature (T_(M(C))) of the at least one copolyamidepresent in the polymer film (P). The polymer film (P) is then preferablystretched in step iv-m) at the temperature to which it is heated priorto step iv-m).

It will be apparent that, in the casting process, in the blowingprocess, in the biaxially oriented polyamide film process and in themultifilm blowing process it is likewise optionally possible to conductstep) in which at least one further polymer (FP) is provided in moltenform in a further extruder and that in that case, correspondingly, stepii) of the process for producing the polymer film (P), in step ii-c), instep ii-b) in step ii-o) and in step ii-m), a film of the at least onecopolyamide and of the at least one further polymer (FP), each in moltenform, is obtained and this is cooled down in accordance with step iii)of the process for producing the polymer film (P) in step iii-c), instep iii-b) in step ii-o) and in step ii-m).

In respect of the optionally conducted step i1), the embodiments andpreferences described above for the optionally conducted step i1) of theprocess for producing the polymer film (P) are correspondinglyapplicable.

Preferably, no step i1) is conducted in the biaxially oriented polyamidefilm process. Preferably, there is thus no further polymer (FP) providedin a further extruder in the biaxially oriented polyamide film process.

The stretched polymer film (P) obtained can, for example, be wound upsubsequently to its production. Methods for this purpose are known tothose skilled in the art. If the stretched polymer film (SP) is obtainedin tubular form, as, for example, in the blowing process and in themultifilm blowing process, the tube can also be slit before being woundup. A slit film can then be wound up on one or more rolls.

Use of the Polymer Film

The polymer film (P) of the invention is preferably used as packagingfilm.

The present invention therefore also provides for the use of the polymerfilm (P) of the invention as packaging film.

For example, the polymer film (P) of the invention can be used astubular pouch packaging, as laterally sealed pouch packaging, asthermoformed packaging, for closable pouches and/or as cushionpackaging.

The present invention is elucidated in detail hereinafter with referenceto examples.

EXAMPLES

The properties of the polymer films (P) were determined as follows:

The viscosity number of copolyamides comprising units derived from aC₃₂-C₄₀ dimer acid was determined in a 0.5% by weight solution ofphenol/o-dichlorobenzene in a weight ratio of 1:1 at 25° C.

The viscosity number of copolyamides and polyimides that do not compriseany units derived from a C₃₂-C₄₀ dimer acid was determined in a 0.5% byweight solution in 96% by weight sulfuric acid at 25° C. according to ENISO 307: 2007+Amd 1: 2013.

The glass transition temperatures and melting temperatures weredetermined according to ISO 11357-1: 2009, ISO 11357-2: 2013 and ISO11357-3: 2011. For this purpose, two heating runs were conducted and theglass transition and melting temperatures were ascertained from thesecond heating run.

The densities of the polyamides were determined by the gas pycnometermethod according to EN ISO 1183-3: 1999.

For determination of the proportion of polyamide-6,36 in thecopolyamide, the copolyamide was hydrolyzed in dilute hydrochloric acid(20%). This protonates the units derived from hexamethylenediamine, withthe chloride ion from the hydrochloric acid forming the counterion. Bymeans of ion exchanger, this chloride ion was then exchanged for ahydroxide ion with release of hexamethylenediamine. By titration with0.1 molar hydrochloric acid, the hexamethylenediamine concentration isthen determined, from which the proportion of polyamide-6,36 in thecopolyamide can be determined.

Tear propagation resistance is determined according to Elmendorf, DINISO 6383-2: 2004 in extrusion direction (MD) and at right angles thereto(TD). The films were conditioned under standard climatic conditions fornon-tropical countries according to DIN EN ISO 291: 2008.

Modulus of elasticity is determined according to ISO 527-3: 1995.

The impact resistance of the polymer film (P) was determined accordingto DIN ISO 7765-2: 1994 with 5 specimens at a relative air humidity of0%, with reporting of the puncture energy in the present context.

The following polymers were used:

Polyamides

-   P-1 nylon-6 from BASF SE®, sold under the Ultramid B40L brand name,    with a viscosity number of 250 mL/g, a glass transition temperature    of 57° C., a melting temperature of 220° C. and a density of 1.153    g/mL.-   P-2 nylon-6 from BASF SE®, sold under the Ultramid B33L brand name,    with a viscosity number of 195 mL/g, a glass transition temperature    of 56° C., a melting temperature of 220° C. and a density of 1.145    g/mL.-   P-3 copolymer of nylon-6 and nylon-6,6 (PA 6/6.6) from BASF SE®,    sold under the Ultramid C40L brand name, with a viscosity number of    250 mL/g, a glass transition temperature of 53° C., a melting    temperature of 190° C. and a density of 1.143 g/mL.-   P-4 copolymer of nylon-6 and nylon-6,6 (PA 6/6.6) from BASF SE®,    sold under the Ultramid C33L brand name, with a viscosity number of    195 mL/g, a glass transition temperature of 55° C., a melting    temperature of 196° C. and a density of 1.144 g/mL.    Copolyamides with Dimer Acid:-   C-1 A copolyamide of nylon-6 and polyamide-6,36, prepared by the    following method:    -   900 kg of caprolactam (component (A)), 83.5 kg of Pripol 1009        from Croda (C₃₆ dimer acid, hydrogenated, component (B1)), 19.9        kg of 85% by weight hexamethylenediamine solution (component        (B2)) in water, 100 g of Polyapp 2557-CTW antifoam reagent        composed of polymethylsiloxane from Polystell do Brazil and 100        kg of water were mixed in a 1930 L tank and blanketed with        nitrogen. The outside temperature of the tank was heated to        290° C. and the mixture present in the tank was stirred at this        temperature for 11 hours. In the first 7 h the mixture was        stirred at elevated pressure, in the next 4 hours under reduced        pressure, during which the water formed was distilled off. The        copolyamide thus obtained was then discharged from the tank,        extruded and pelletized. After the pellets of the copolyamide        obtained had been extracted with water at 95° C. for 4×6 hours,        the copolyamide was dried at 90 to 140° C. in a nitrogen stream        for 10 hours. The viscosity number was 246 mL/g, the glass        transition temperature was 49° C. and the melting temperature        was 211° C. The proportion of polyamide-6,36 in the copolyamide,        based on the total weight of the copolyamide, was 10.5% by        weight; the density was 1.116 g/mL.-   C-2 A copolyamide of nylon-6 and polyamide-6,36, prepared by the    following method:    -   1039 kg of caprolactam (component (A)), 216 kg of Pripol 1009        from Croda (C₃₆ dimer acid, hydrogenated, component (B1)), 51.7        kg of 85% by weight hexamethylenediamine solution (component        (B2)) in water, 100 g of Polyapp 2557-CTW antifoam reagent from        Polystell do Brazil and 142 kg of water were mixed in a 1930 L        tank and blanketed with nitrogen. The outside temperature of the        tank was heated to 290° C. and the mixture was stirred at this        temperature for 11 hours. In the first 7 h the mixture was        stirred at elevated pressure, in the next 4 hours under reduced        pressure, during which the water formed was distilled off. The        copolyamide obtained was discharged from the tank, extruded and        pelletized. The pellets of the copolyamide obtained were        extracted with water at 95° C. for 4×6 hours and then dried at        90 to 140° C. in a nitrogen stream for 10 hours. The copolyamide        obtained had a viscosity number of 244 mL/g, a glass transition        temperature of 44° C. and a melting temperature of 203° C. The        proportion of polyamide-6,36 in the copolyamide, based on the        total weight of the copolyamide, was 20.8% by weight; the        density was 1.095 g/mL.-   C-3 A copolyamide of nylon-6 and polyamide-6,36, prepared by the    following method:    -   932 kg of caprolactam (component (A)), 323.2 kg of Pripol 1009        from Croda (C₃₆ dimer acid, hydrogenated, component (B1)), 77.84        kg of 85% by weight hexamethylenediamine solution (component        (B2)) in water and 153 kg of water were mixed in a 1930 L tank        and blanketed with nitrogen. The outside temperature of the tank        was heated to 290° C. and the mixture was stirred at this        temperature for 11 hours. In the first 7 h the mixture was        stirred at elevated pressure, in the next 4 hours under reduced        pressure, during which water formed was distilled off. The        copolyamide obtained was discharged from the tank, extruded and        pelletized. The pellets of the copolyamide obtained were        extracted with water at 95° C. for 4×6 hours and then dried at        90 to 140° C. in a nitrogen stream for 10 hours. The copolyamide        obtained had a viscosity number of 259 mL/g, a glass transition        temperature of 38° C. and a melting temperature of 188° C. The        proportion of polyamide-6,36 in the copolyamide, based on the        total weight of the copolyamide, was 30.3% by weight; the        density was 1.076 g/mL.-   C-4 A copolyamide of nylon-6 and polyamide-6,36, prepared by the    following method:    -   932 kg of caprolactam (component (A)), 322 kg of Empol 1061 from        BASF SE (C₃₆ dimer acid, unhydrogenated, component (B1)), 77.84        kg of 85% by weight hexamethylenediamine solution (component        (B2)) in water and 153 kg of water were mixed in a 1930 L tank        and blanketed with nitrogen. The outside temperature of the tank        was heated to 290° C. and the mixture was stirred at this        temperature for 11 hours. In the first 7 h the mixture was        stirred at elevated pressure, in the next 4 hours under reduced        pressure, during which water formed was distilled off. The        copolyamide obtained was discharged from the tank, extruded and        pelletized. The pellets of the copolyamide obtained were        extracted with water at 95° C. for 4×6 hours and then dried at        90 to 140° C. in a nitrogen stream for 10 hours. The copolyamide        obtained had a viscosity number of 212 mL/g, a glass transition        temperature of 38° C. and a melting temperature of 187° C. The        proportion of polyamide-6,36 in the copolyamide, based on the        total weight of the copolyamide, was 28.9% by weight; the        density was 1.076 g/mL.

Further Polymer (FP)

-   FP-1 Low-density polyethylene (LDPE) from LyondellBasell®, sold    under the Lupolen 2420 F brand name with an MFR (melt flow rate)    (190° C./2.16 kg) of 0.75 g/10 min.-   FP-2 Low-density polyethylene (LDPE) from LyondellBasell®, sold    under the Lupolen 3020 K brand name with an MFR (melt flow rate)    (190° C./2.16 kg) of 4 g/10 min.-   FP-3 Anhydride-modified linear low-density polyethylene (LLDPE) from    DuPont®, sold under the Bynel 4104 brand name with an MFR (melt flow    rate) (190° C./2.16 kg) of 1.1 g/10 min.-   FP-4 Anhydride-modified linear low-density polyethylene (LLDPE) from    DuPont®, sold under the Bynel 4105 brand name with an MFR (melt flow    rate) (190° C./2.16 kg) of 4 g/10 min.-   FP-5 A poly(ethyl-vinyl alcohol) (EVOH) from Kuraray®, sold under    the EVAL F171B brand name with an MFR (melt flow rate) (210° C./2.16    kg) of 1.8 g/10 min and an ethylene content of 32 mol %.-   FP-6 A poly(ethyl-vinyl alcohol) (EVOH) from Kuraray®, sold under    the EVAL L171B brand name with an MFR (melt flow rate) (210° C./2.16    kg) of 4 g/10 min and an ethylene content of 27 mol %.

Production of Monofilms by a Casting Process

For production of monofilms, a 7-layer cast film system from Collin®with a die head width of 800 mm was used. Thus, 7 extruders were used. 6of the extruders had a diameter of 30 mm (extruders B, C, D, E, F, G);one extruder had a diameter of 45 mm (extruder A). Each of the 7extruders were loaded with the same component. The melt from extruder Awas in contact with the casting roll; the melt from extruder G was thefurthest removed therefrom. The sequence of the layers was A, B, C, D,E, F, G. The polymer films produced had a thickness of 100 μm and thelayers had a layer thickness of 15/14/14/14/14/14/15 μm. The componentsused and the results of the measurement of the tear propagationresistance, modulus of elasticity and puncture resistance are specifiedin table 1. The percentages by weight of component (B) specified intable 1 are understood to mean the percentages by weight of unitsderived from component (B) (polyamide-6,36 units) in the copolyamide,based on the total weight of the copolyamide.

TABLE 1 V1 V2 V3 B4 B5 Component P-2 P-4 C-1 C-2 C-3 Component (B) [% bywt.] — — 10.5 20.8 30.3 Tear [mN] 2337 2601 3076 6329 7706 propagation(8 N (8 N (8 N (32 N (32 N resistance pendulum) pendulum) pendulum)pendulum) pendulum) (MD) Tear [mN] 2046 3337 2734 6087 7588 propagation(8 N (8 N (8 N (8 N (8 N resistance (TD) pendulum) pendulum) pendulum)pendulum) pendulum) Modulus of [MPa] 758 439 713 621 514 elasticity (MD)Modulus of [MPa] 756 469 684 621 365 elasticity (TD)

Production of Multilayer Films by a Casting Process

Multilayer films comprising three different polymers were produced inthe above-described 7-layer cast film system from Collin®. Themultilayer films obtained had a thickness of 100 μm and the layers had alayer thickness of 15/14/14/14/14/14/15 μm. The extruders of the castfilm system were charged with the components in accordance with themakeup of the multilayer films specified in table 2. The percentages byweight of component (B) specified in table 2 are understood to mean thepercentages by weight of units derived from component (B)(polyamide-6,36 units) in the copolyamide, based on the total weight ofthe copolyamide. Table 2 also states the properties of the multilayerfilm produced.

TABLE 2 V6 V7 V8 B9 B10 Makeup FP-2 // FP-4 // FP-2 // FP-4 // FP-2 //FP-4 // FP-2 // FP-4 // FP-2 // FP-4 // P-2 // P-2 // P-2 // P-4 // P-4// P-4 // C-1 // C-1 // C-1 // C-2 // C-2 // C-2 // C-3 // C-3 // C-3 //FP-4 // FP-2 FP-4 // FP-2 FP-4 // FP-2 FP-4 // FP-2 FP-4 // FP-2Component (B) [% by wt.] — — 10.5 20.8 30.3 Tear [mN] 1293 1850 17022841 5874 propagation (8 N pendulum) (8 N pendulum) (8 N pendulum) (8 Npendulum) (8 N pendulum) resistance (MD) Tear [mN] 1438 1998 2131 370915856 propagation (8 N pendulum) (8 N pendulum) (8 N pendulum) (8 Npendulum) (32 N pendulum) resistance (TD) Puncture energy [J] 0.3 0.30.3 1.4 2.1 Modulus of [MPa] 437 347 431 408 353 elasticity (MD) Modulusof [MPa] 432 344 442 403 328 elasticity (TD)

Production of Multilayer Films by a Casting Process

Multilayer films comprising five different polymers were produced in theabove-described 7-layer cast film system from Collin®. The multilayerfilms obtained had a thickness of 100 μm and the layers had a layerthickness of 15/14/14/14/14/14/15 μm. The extruders of the cast filmsystem were charged with the components in accordance with the makeup ofthe multilayer films specified in table 3. The percentages by weight ofcomponent (B) specified in table 3 are understood to mean thepercentages by weight of units derived from component (B)(polyamide-6,36 units) in the copolyamide, based on the total weight ofthe copolyamide. Table 3 also states the properties of the multilayerfilm produced.

TABLE 3 V11 V12 V13 B14 B15 Makeup FP-2 // FP-4 // FP-2 // FP-4 // FP-2// FP-4 // FP-2 // FP-4 // FP-2 // FP-4 // P-2 // FP-6 // P-2 P-4 //FP-6 // P-4 // C-1 // FP-6 // C-1 // C-2 // FP-6 // C-2 // C-3 // FP-6// C-3 // // FP-4 // FP-2 FP-4 // FP-2 FP-4 // FP-2 FP-4 // FP-2 FP-4 //FP-2 Component (B) [% by wt.] — — 10.5 20.8 30.3 Tear propagation [mN]3649 4344 4257 13206 11311 resistance (MD) (8 N pendulum) (8 N pendulum)(8 N pendulum) (32 N pendulum) (32 N pendulum) Tear propagation [mN]3909 8812 6667 17953 14408 resistance (TD) (8 N pendulum) (32 Npendulum) (32 N pendulum) (8 N pendulum) (32 N pendulum) Modulus of[MPa] 717 629 723 698 628 elasticity (MD) Modulus of [MPa] 721 650 721679 681 elasticity (TD)

Production of Monofilms by the Blowing Process

Monofilms were produced in a 7-layer blown film system from Collin®having a die head diameter of 180 mm. Of the 7 extruders, 6 had adiameter of 30 mm (extruders B, C, D, E, F, G) and one a diameter of 45mm (extruder A). The melt from extruder was on the inside of the bubble;the melt from extruder G was on the outside. The sequence of the layers,from the inside outward, was A, B, C, D, E, F, G. The monofilms producedhad a thickness of 100 μm and the layers had a layer thickness of15/14/14/14/14/14/15 μm in the monofilms. All the extruders were loadedwith the same component. The films were slit before they were wound up.

The components used and the properties of the monomaterial films arespecified in table 4. The percentages by weight of component (B)specified in table 4 are understood to mean the percentages by weight ofunits derived from component (B) (polyamide-6,36 units) in thecopolyamide, based on the total weight of the copolyamide.

TABLE 4 V16 V17 V18 B19 B20 Component P-1 P-3 C-1 C-2 C-3 Component (B)[% by — — 10.5 20.8 30.3 wt.] Tear [mN] 1913 4783 3083 3804 9548propagation (8 N (8 N (8 N (32 N (32 N resistance (MD) pendulum)pendulum) pendulum) pendulum) pendulum) Tear [mN] 1823 5325 2909 576722287 propagation (8 N (8 N (8 N (8 N (8 N resistance (TD) pendulum)pendulum) pendulum) pendulum) pendulum) Modulus of [MPa] 635 411 536 412329 elasticity (MD) Modulus of [MPa] 656 410 510 446 356 elasticity (TD)

Production of Multilayer Films in a Blowing Process

Multilayer films comprising three different materials were produced in a7-layer blown film system from Collin® with a die head diameter of 180mm. Of the 7 extruders, 6 had a diameter of 30 mm and one a diameter of45 mm. The multilayer films obtained had a thickness of 100 μm and thelayers had a layer thickness of 15/14/14/14/14/15 μm. The extruders ofthe blown film system were charged with the components in accordancewith the makeup of the multilayer films specified in table 5. Table 5also states the properties of the multilayer films produced. Thepercentages by weight of component (B) specified in table 5 areunderstood to mean the percentages by weight of units derived fromcomponent (B) (polyamide-6,36 units) in the copolyamide, based on thetotal weight of the copolyamide.

TABLE 5 V21 V22 V23 B24 B25 Makeup FP-1 // FP-3 // FP-1 // FP-3 // FP-1// FP-3 // FP-1 // FP-3 // FP-1 // FP-3 // P-1 // P-1 // P-1 // P-3 //P-3 // P-3 // C-1 // C-1 // C-1 // C-2 // C-2 // C-2 // C-3 // C-3 //C-3 // FP-3 // FP-1 FP-3 // FP-1 FP-3 // FP-1 FP-3 // FP-1 FP-3 // FP-1Component (B) [% by — — 10.5 20.8 30.3 wt.] Tear propagation [mN] 14612826 1950 3109 5181 resistance (MD) (8 N pendulum) (8 N pendulum) (8 Npendulum) (8 N pendulum) (8 N pendulum) Tear propagation [mN] 1461 28242122 3468 4318 resistance (TD) (8 N pendulum) (8 N pendulum) (8 Npendulum) (8 N pendulum) (8 N pendulum) Puncture energy [J] 1.3 0.6 1.33.7 4.0 Modulus of [MPa] 377 312 321 316 280 elasticity (MD) Modulus of[MPa] 391 307 356 326 307 elasticity (TD)

Production of Multilayer Films in a Blowing Process

Multilayer films comprising five different polymers were produced in a7-layer blown film system from Collin® with a die head diameter of 180mm. Of the 7 extruders, 6 had a diameter of 30 mm and one a diameter of45 mm. The multilayer films obtained had a thickness of 100 μm and thelayers had a layer thickness of 15/14/14/14/14/15 μm. The extruders ofthe blown film system were charged with the components in accordancewith the makeup of the multilayer films specified in table 6. Table 6also states the properties of the multilayer films produced. Thepercentages by weight of component (B) specified in table 6 areunderstood to mean the percentages by weight of units derived fromcomponent (B) (polyamide-6,36 units) in the copolyamide, based on thetotal weight of the copolyamide.

TABLE 6 V26 V27 V28 B29 B30 Makeup FP-1 // FP-3 // FP-1 // FP-3 // FP-1// FP-3 // FP-1 // FP-3 // FP-1 // FP-3 // P-1 // FP-5 // P-1 // P-3 //FP-5 // P-3 // C-1 // FP-5 // C-1 // C-2 // FP-5 // C-2 // C-3 // FP-5// C-3 // FP-3 // FP-1 FP-3 // FP-1 FP-3 // FP-1 FP-3 // FP-1 FP-3 //FP-1 Component (B) [% by — — 10.5 20.8 30.3 wt.] Tear propagation [mN]1975 6401 1875 6194 10042 resistance (MD) (8 N pendulum) (32 N pendulum)(8 N pendulum) (32 N pendulum) (32 N pendulum) Tear propagation [mN]2325 8062 1975 9637 13530 resistance (TD) (8 N pendulum) (8 N pendulum)(8 N pendulum) (8 N pendulum) (8 N pendulum) Puncture energy [J] 0.7 0.81.2 1.2 0.9 Modulus of [MPa] 814 709 878 778 714 elasticity (MD) Modulusof [MPa] 793 710 421 672 593 elasticity (TD)

Production of Monofilms in the Blowing Process

Monofilms were produced in a 7-layer blown film system from Collin® witha die head diameter of 180 mm. Of the 7 extruders, 6 had a diameter of30 mm and one a diameter of 45 mm. The monomaterial films produced had athickness of 100 μm and the layers had a layer thickness of15/14/14/14/14/14/15 μm. All the extruders were loaded with the samecomponent.

The components used and the properties of the monofilms are specified intable 7. The percentages by weight of component (B) specified in table 7are understood to mean the percentages by weight of units derived fromcomponent (B) (polyamide-6,36 units) in the copolyamide, based on thetotal weight of the copolyamide.

TABLE 7 V31 V32 B33 Component P-1 P-3 C-4 Component (B) [% by — — 28.9wt.] Tear propagation [mN] 1910 4408 8654 resistance (MD) (8N pendulum)(8N (32N pendulum) pendulum) Tear propagation [mN] 1736 4057 11436resistance (TD) (8N pendulum) (8N (32N pendulum) pendulum) Modulus ofelasticity [MPa] 666 484 297 (MD) Modulus of elasticity [MPa] 678 457299 (TD)

Production of Multilayer Films in the Blowing Process

Multilayer films were produced in a 7-layer blown film system fromCollin® with a die head diameter of 180 mm. Of the 7 extruders, 6 had adiameter of 30 mm and one a diameter of 45 mm. The monomaterial filmsproduced had a thickness of 100 μm and the layers had a layer thicknessof 15/14/14/14/14/14/15 μm. All the extruders were loaded with the samecomponent.

The components used and the properties of the monomaterial films arespecified in table 8. The percentages by weight of component (B)specified in table 8 are understood to mean the percentages by weight ofunits derived from component (B) (polyamide-6,36 units) in thecopolyamide, based on the total weight of the copolyamide.

TABLE 8 V34 V35 B36 Makeup FP-1 // FP-3 // FP-1 // FP-3 // FP-1 // FP-3// P-1 // FP-5 // P-1 // P-3 // FP-5 // P-3 // C-4 // FP-5 // C-4 //FP-3 // FP-1 FP-3 // FP-1 FP-3 // FP-1 Component (B) [% by — — 28.9 wt.]Tear propagation [mN] 1932 3079 15149 resistance (MD) (8N pendulum) (32Npendulum) (32N pendulum) Tear propagation [mN] 2276 6124 10110resistance (TD) (8N pendulum) (8N pendulum) (32N pendulum) Modulus of[MPa] 990 824 746 elasticity (MD) Modulus of [MPa] 966 784 728elasticity (TD)

The above examples show that the copolyamide of the invention cansignificantly increase the tear propagation resistance of the polymerfilms (P) both in extrusion direction and at right angles thereto. Themodulus of elasticity and puncture resistance of the polymer films (P)of the invention are also within a range acceptable for practical use,and so the polymer films (P) of the invention have advantageousproperties overall, especially as packaging films.

1. A polymer film, comprising: a copolyamide, which is prepared bypolymerizing components: (A) from 15% to 84% by weight of at least onelactam, (B) from 16% to 85% by weight of a monomer mixture comprisingcomponents: (B1) a C₃₂-C₄₀ dimer acid; and (B2) a C₄-C₁₂ diamine,wherein percentages by weight of the components (A) and (B) are based ona total weight of the components (A) and (B).
 2. The polymer filmaccording to claim 1, wherein the component (A) is selected from thegroup consisting of 3-aminopropanolactam, 4-aminobutanolactam,5-aminopentanolactam, 6-aminohexanolactam, 7-aminoheptanolactam,8-aminooctanolactam, 9-aminononanolactam, 10-aminodecanolactam,11-aminoundecanolactam and 12-aminododecanolactam.
 3. The polymer filmaccording to claim 1, wherein the component (B) comprises from 45 to 55mol % of the component (B1) and from 45 to 55 mol % of the component(B2), based on a total molar amount of the component (B).
 4. The polymerfilm according to claim 1, wherein the component (B2) is selected fromthe group consisting of tetramethylenediamine, pentamethylenediamine,hexamethylenediamine, decamethylenediamine and dodecamethylenediamine.5. The polymer film according to claim 1, wherein the component (B1) isprepared from one or more unsaturated fatty acids selected from thegroup consisting of an unsaturated C₁₆ fatty acid, an unsaturated C₁₈fatty acid, and an unsaturated C₂₀ fatty acid.
 6. The polymer filmaccording to claim 1, wherein the copolyamide has a viscosity numberfrom 150 to 300 ml/g, determined in a 0.5% by weight solution of thecopolyamide in a mixture of phenol/o-dichlorobenzene in a weight ratioof 1:1.
 7. The polymer film according to claim 1, wherein thecopolyamide has a glass transition temperature ranging from 20 to 50° C.8. The polymer film according to claim 1, wherein the copolyamide has amelting temperature ranging from 150 to 210° C.
 9. The polymer filmaccording to claim 1, comprising: a first layer comprising thecopolyamide, and an additional layer, wherein the additional layercomprises an additional polymer selected from the group consisting of apolyolefin, a poly(ethylene-vinyl alcohol), a poly(ethylene-vinylacetate), a polyethylene terephthalate, a polyvinylidene chloride and amaleic anhydride-grafted polyolefin.
 10. The polymer film according toclaim 1, produced in a casting process, in a blowing process, in abiaxially oriented polyamide film process, or in multifilm blowingprocess.
 11. The polymer film according to claim 1, wherein the polymerfilm has a thickness ranging from 0.1 μm to 1 mm.
 12. The polymer filmaccording to claim 1, wherein the copolyamide is a random copolymer. 13.A process for producing the polymer film according to claim 1,comprising: preparing the copolyamide in a molten form in a firstextruder, extruding the copolyamide in the molten form out of the firstextruder through a die to obtain a film of the copolyamide in the moltenform, and cooling the film of the copolyamide in the molten form, withsolidification of the copolyamide to obtain the polymer film.
 14. Apackaging film, comprising the polymer film according to claim 1.